Rough E

Structure

-          Network of flattened membranes connected to the nuclear envelope.

-          Contains RIBOSOMES

Functions

-          Site of Protein synthesis: RIBOSOMES synthesise proteins: specifically lysosomes, membranes of organelles, excreted proteins 

-          Protein modification: folding and post-transcriptional modifications occur

-         
Transport: sends proteins to the Golgi apparatus for further processing

-packages proteins via vesicles for further modification in the golgi

Smooth ER

Structure

-          Continuous extension of the rough ER, located more distantly from the nucleus.

-          Does not contain ribosomes.

Functions 

-          Lipid synthesis: produces phospholipids for cell membranes. 

-          Detoxification: breaks down drugs and toxins (abundant in liver cells)

-          Calcium storage: important in muscles contraction (sarcoplasmic reticulum in muscles)